Distribution of premovement slow cortical potentials associated with self-paced hand movements in monkeys.

With electrodes chronically implanted on the surface and in the depth of the cerebral cortex, field potentials were led from various cortical areas of the bilateral hemispheres of monkeys performing self-paced hand movements. In the hemisphere contralateral to the moving hand, surface negative-depth positive, slowly increasing premovement potentials were recorded in wider portions of the premotor cortex and in the forelimb areas of the motor and somatosensory cortices. In the ipsilateral hemisphere, the potentials of relatively large amplitudes were often obtained in the premotor cortex, whereas either small or no premovement potentials were recorded in the motor and somatosensory cortices.